The examination of the extermination of the chronic arsenic poisoning was tried in the Inner Mongolia and Shanxi in China. Whether the hyperkeratosis was able to be improved to the patiant with the chronic arsenic poisoning especially in this research because of the abatement of the amount of the exposure of the arsenic was verified. The respondent to a survey is a villager who resides in the Inner Mongolia, Baotou City, and the population of this village is 430 families, and 2080 people. The villager makes a living by agriculture and stock raising, and family's life and dining habit are almost the same. 96 people were elected from the villager, and the doctors of dermatology examined it. The measurement of the arsenic in urine and 8- OHdG concentrations was executed. The standard value 0.05ppm or less of the arsenic of the drinking water of China was supplied to the reduction of the inorganic arsenic exposure to the patients. This well water (water supply of tube type) was used the dr
… Moreinking water and to cook. The patient's arsenic exposure has decreased to about 1/2 by improving the well water. It is thought that the improvement is admitted as for the oxidative DNA damage because of the reduction of the inorganic arsenic exposure, and this result contributes to the decrease in a carcinogenic risk. The improvement of the hyperkeratosis that was the trouble of life and the labor of the patiant with the chronic arsenic poisoning was observed for five years. The improvement of the hyperkeratosis is 20 of 33, there was no change 11 people, two people are the symptom exacerbations. The hyperkeratosis was the tendency to the improvement, and was remarkable like the serious illness person from the reduction of the inorganic arsenic exposure year first. In addition, these patient groups investigated the improve of the skin manifestation in year fifth. The number of patients who had inspected it was gradually 25 decreasing people. In the investigation of year fifth, the improvements of the hyperkeratosis were only two people. The serious illness person admitted the improvement of the hyperkeratosis though a similar research was executed in Shanxi. The slight illness person lacked the improvement desire of the hyperkeratosis, and the inorganic arsenic exposure was continued. It was thought that the drinking water and food from which the reduction of a further inorganic arsenic exposure was expected were necessary for an effective improvement of the hyperkeratosis. Less